kartavya avaśya ei, anyathā pratyavāya
bhavet-bhavet; kriyā-the verb; vidhi-liṅ-an injunction of the imperative mood; sei-that; ihā-here; kaya-says; kartavya-to be done; avaśya-certainly; ei-this; anyathā-otherwise; pratyavāya-detriment.
Here the use of the verb "bhavet," which is in the imperative mood, tells us that this certainly must be done. Noncompliance would be abandonment of duty.
ei-this; vāñchā-desire; yaiche-just as; kṛṣṇa-of Lord Kṛṣṇa; prākaṭya-for the manifestation; kāraṇa-reason; asura-saṁhāra-the killing of demons; ānuṣaṅga-secondary; prayojana-reason; ei mata-like this; caitanya-as Lord Caitanya Mahāprabhu; kṛṣṇa-Lord Kṛṣṇa; pūrṇa-full; bhagavān-the Supreme Personality of Godhead; yuga-dharma-the religion of the age; pravartana-initiating; nahe-is not; tāṅra-of Him; kāma-the desire.